Wiki info about P-63A-5

Bell P-63A-1/A-5 (Model 33) Kingcobra Army Fighter
A single-seat, closed-canopy, all-metal monoplane fighter with retractable landing gear and a nose strut. The P-63 Kingcobra was developed as an improved version of the P-39 Airacobra and had a similar layout, with the engine located just behind the cockpit.
Work on the plane, originally designated the XP-39E, began in February 1941. The first prototype, designated XP-63, flew on December 7, 1942, and production of the P-63A-1 (Model 33) began in October 1943, along with the P-39.
The general layout of the P-39 Kingcobra was preserved, but the P-63 featured new, streamlined wings. In order to remedy the P-39's main weakness, a propensity to falling into a flat spin, the area of the vertical tail fin was increased and the aft section of the fuselage was lengthened.
The first production models were equipped with a V-12 liquid-cooled Allison V-1710-93 engine (1325 hp). The aircraft was armed with a Colt-Browning M4 37mm machine gun with 30 rounds and 2 synchronous Colt-Browning M2.5 12.7mm machine guns with 270 rounds per gun. An additional two M2.5s with 250 rounds each were placed in the wing compartments.
Aircraft of both series (except some A-1 planes) were fitted with a ventral pylon which could hold a fuel tank of 75 gallons (284 liters) or one 500-lb (227-kg) bomb.
The aircraft was continually tweaked from one production run to the next, improving its ability to support troops on the field. However, the differences between the A-1 and the A-5 were only slight. The most significant difference, though not a visible one, was the increase in armor from 40 kilograms to 81. 50 P-63A-1 and 20 P-63A-5 planes were produced.
The Red Army became the main consumers of the P-63A. Deliveries to the Soviet Union began in the summer of 1944, via Alaska and the Northwest Staging Route. The P-63A began to support Soviet anti-aircraft operations in the spring of 1945.
The Soviet version of the P-63A differed from the American in one important feature: the presence of a crank to start the engine. In addition, the Soviets equipped the plane with FAB-100 and FAB-250 bombs under the fuselage.